NESA Physics Origins of the Elements
4 sample questions with marking guides and sample answers · Avg. score: 71%
According to the Big Bang theory, the strong nuclear force separated from the electromagnetic and weak forces around s after the expansion of the universe began.
Explain how this separation enabled the formation of hadrons.
Reveal Answer
The strong nuclear force is mediated by the exchange of gluons. Quarks could now exchange gluons and interact, and hadrons are formed by quarks exchanging gluons and binding together.
| Descriptor | Marks |
|---|---|
States that the strong nuclear force is mediated by the exchange of gluons | 1 |
Describes that quarks could now exchange gluons and interact | 1 |
Explains that hadrons are formed by quarks exchanging gluons and binding together | 1 |
Matter is converted to energy by nuclear fusion in stars.
If the star Alpha Centauri converts mass to energy at the rate of 6.6 × 10^9 kg s−1, then the power generated is closest to
2.0 × 10^18 W
2.0 × 10^18 J
6.0 × 10^26 W
6.0 × 10^26 J
Reveal Answer
2.0 × 10^18 W
Incorrect. This value incorrectly calculates power by multiplying the mass rate by the speed of light () instead of .
2.0 × 10^18 J
Incorrect. This option uses the incorrect formula ( instead of ) and the wrong unit for power, which should be Watts, not Joules.
6.0 × 10^26 W
Correct. Power is the rate of energy generation, calculated using . Multiplying by gives approximately .
6.0 × 10^26 J
Incorrect. Although the numerical calculation is correct, the unit for power is Watts (Joules per second), not Joules.
Many scientists have performed experiments to explore the interaction of light and matter.
Analyse how evidence from at least THREE such experiments has contributed to our understanding of physics.
Reveal Answer
Answers could include:
Reference to:
- Black body radiation experiments and the development of quantum physics
- Photoelectric experiments and the development of quantum physics
- Spectroscopy experiments and the development of astrophysics and the atomic model
- Polarisation experiments and the development of the wave nature of light
- Interference and diffraction and the development of the wave model of light
- Cosmic gamma rays and the development of theory of special relativity and/or the standard model.
| Descriptor | Marks |
|---|---|
| 8 |
| 7 |
The student response meets all criteria of the 5-mark band, and additionally meets the majority of criteria in the 7-mark band. | 6 |
| 5 |
The student response meets all criteria of the 3-mark band, and additionally meets the majority of criteria in the 5-mark band. | 4 |
Provides some information about evidence from an experiment AND/OR a link to physics | 3 |
The student response meets all criteria of the 1-mark band, and additionally meets the majority of criteria in the 3-mark band. | 2 |
Provides some relevant information | 1 |
None of the above | 0 |
Identify the defining feature of a black body.
All frequencies of electromagnetic radiation are absorbed and emitted.
Light with two wavelength peaks is emitted at a specific temperature.
Electrons are emitted in the presence of all frequencies of light.
The peak of its spectral output does not vary with temperature.
Reveal Answer
All frequencies of electromagnetic radiation are absorbed and emitted.
A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence, and emits radiation across a continuous spectrum based on its temperature.
Light with two wavelength peaks is emitted at a specific temperature.
The spectral distribution of black-body radiation is a continuous curve with a single peak intensity wavelength determined by the temperature, not two peaks.
Electrons are emitted in the presence of all frequencies of light.
This describes a misunderstood version of the photoelectric effect; a black body is defined by its perfect absorption and thermal emission of electromagnetic radiation, not by electron emission.
The peak of its spectral output does not vary with temperature.
According to Wien's Displacement Law, the peak wavelength of emission is inversely proportional to temperature (), meaning the peak shifts to shorter wavelengths as the object gets hotter.